Assesment of procoagulant activity of microparticles
Author
Sørensen, Ditte
Term
4. term
Publication year
2012
Pages
51
Abstract
Microparticles (MP) are small cell-derived vesicles with procoagulant properties and potential value as diagnostic and prognostic biomarkers, but their clinical use is limited by insufficient standardization of pre-analytics and assays. This study aimed to evaluate two commercial solid-phase assays, the Zymuphen Microparticle Activity assay (for phosphatidylserine-positive MPs) and the Zymuphen MP-TF assay (for tissue factor–bearing MPs), and to determine how sample preparation influences measurements. Plasma from healthy adults and cancer patients was analyzed using three centrifugation protocols (the manufacturer’s recommendation, a widely cited literature protocol, and a local protocol), in both fresh and frozen aliquots, with assessment of calibration, dynamic range, and intra- and inter-assay variability. All three centrifugations produced platelet-free plasma, yet measured levels of phosphatidylserine-positive MPs varied within the same donor across protocols, suggesting effects of residual platelets. Both assays showed differences between fresh and frozen samples. Preliminary data indicate that both assays can distinguish healthy individuals from cancer patients. These findings highlight that pre-analytical handling critically affects MP measurements and that further standardization and validation are needed.
Mikropartikler (MP) er små celleafledte vesikler med prokoagulerende egenskaber og potentiel værdi som diagnostiske og prognostiske biomarkører, men manglende standardisering af præanalytik og analyser begrænser anvendelsen. Dette studie havde til formål at vurdere to kommercielle solid-phase assays, Zymuphen Microparticle Activity (for fosfatidylserin‑positive MP) og Zymuphen MP‑TF (for vævsfaktorbærende MP), og undersøge hvordan prøveforberedelse påvirker målingerne. Plasma fra raske voksne og kræftpatienter blev analyseret under tre forskellige centrifugeringsprotokoller (producentens anbefaling, den hyppigst anvendte i litteraturen og en lokal protokol), i både friske og frosne aliquoter, med evaluering af kalibrering, dynamisk område samt intra‑ og inter‑assay variation. Alle tre centrifugeringer gav trombocytfrit plasma, men de målte mængder af fosfatidylserin‑positive MP varierede inden for samme donors prøve på tværs af protokoller, hvilket tyder på indflydelse fra resttrombocytter. Begge assays viste forskelle mellem friske og frosne prøver. Foreløbige data antyder, at begge assays kan skelne mellem raske individer og kræftpatienter. Resultaterne understreger, at præanalytisk håndtering er afgørende for reproducerbare MP‑målinger og at yderligere standardisering og validering er nødvendig.
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